Botticelli's work recreates that image of the sea and sky soothed by the soft power of Venus. The sea in his painting is lulled and luxuriant. It is a marvellous artistic creation, this sea: up close, the painterly freedom is a surprise (try zooming on the Google Art Project link, above). To create the delicate ripples that animate the sea's green surface, Botticelli flicked little wisps of white in quick twists of his brush.

The magic somehow lies in the relationship between the smooth paleness of Venus and the sea's green. Even though Botticelli paints a sea of deep calm, the little wavelets are necessary because they recede from the eye, so making us see the water as a plane reaching back towards the depths of the canvas, across which Venus approaches. She comes forward, on the edge of the onlooker's reality. The picture glories in the sense of uncanny movement, of Venus gliding out of the distance, as pink flowers float down, their slow descent implying that around Venus the air itself has warmed and stilled – as Lucretius has it, "the sky is calmed".

Zephyrus and Aura, the airborne characters wafting her forward with their breath, float in a motionless, weightless sky, locked in an embrace. Venus enacts her influence, and her followers make love in the air, free of all fetters, all restrictions, even that of gravity. Meanwhile, Venus poses in a graceful curve, her knee-length hair held in front of her, a hand covering one breast. She tilts her head and there is an indefinable look in her eyes: they are at once focused and looking past us.

Her nakedness is genuinely divine. She preserves a portion of modesty not because this is a prudish painting, but because the totally revealed nudity of a god might blind or madden the beholder. There is an almost tangible sense of divine power when you look at this image. It is no disguised Christian allegory. It is Venus and Venus alone we are seeing. She approaches, she is near. Her beauty seems to perfume the air around us. Her form sinks into the deep mind. She is to be worshipped as a pagan deity reborn.

The power of Botticelli's painting is that it brings an ancient religion back to life. To love this image is to worship the ancient Roman gods. Hail Venus!